Conductor for high-frequency work



March 27, 1928.

M. OSNOS ET AL CONDUCTOR FOR HIGH PREQUENCY WORK Filed 0621. 20. 1925wuwtoz MENDEL OSNOS Richard KuMmcH g'fhe'w Patented Mar. 27, 1928.

` UNITED STATES PATENT oFFlcE;

MENDEL OSNOS AND RICHARD .KUMMICH, OF BERLIN, GERMANY, ASSIGNORS TO eGESELLSCHAFT FR DRAHTLOSE TELEGRAPHIE IB. H., OE BERLIN, GERMANY, A

CORPORATION OF GERMANY.

CONDUCTOR FOR HIGH-FREQUENCY WORX.

Application led October 20, 1925, Serial No. 63,617, and in GermanySeptember 5, 1924. l

Our invention relates to inductance devices using a magnetic materialand, more particularly, -to a novel form of conductor, especiallyadapted for high frequency work 5 Where large amounts of heat must bedissipated.

An object of the invention is to providea conductor of the above kindwhich will be cheap to make and eicient in use.

vOther objects will be apparent from the following description andappended claims when considered with the accompanying drawing in which,

Fig. l illustrates a conductor made according to the invention.

Fig. 2 is a modification, showing the conductor bent upon itself, and

Figs. Sand lc-represent further modilications in cross-section.

The subject matter of the invention 1s a current conductor for highfrequency purposes, which may act, for instance, as a choke coil,transformer, frequency changer,

coupling means, and the like'. In short, it 25,1nay be used for all suchservices for which heretofore the usual transformers or choke coils havebeen employed such as, for instance, for key work and telephony.

In .the attempt tol utilize iron and other magnetic materials for thesepurposes, one meets this difliculty that the energy losses become verygreat for the reason that for a small volume of iron, a high number ofampere turns per centimeter are necessary.

This'holds true particularly for very high frequencies. Incidentallythere occurs pronounced-heating of the arrangement, while, on the otherhand, it has heretofore not been possible to provide adequate cooling,on the ground that the known coil arrangements constitute concentratedheatlng centers presenting comparatively small cooling sur-In/accordance with the present invention,

the said disadvantage is obviated because vthe iron constitutes thesurface of the conductor or the iron covers the latter, and further, theconductor is elongated in shape and arrangeii'ient. rlhis advantage isthereby 5u obtainedfviz that in virtue of the high overload capacity'ofthe current conductor, a

high number of ampere-turns per cubic centimeter may be used, while atthe same time, on account of the arrangement chosen, the length of themagnetic flux pathremains within low limits.

The iron or other suitable magnetic material can be placed upon thesurface of the linear conductor by various processes. For instance, itmay be deposited by galvanic precipitation or deposition, by theso-called bimetal drawing method, by spraying, etc. However, it is ofconsiderably greater advantage` to continuously wrap around the surfaceof the conductor a very line, most suitably insulated capillary wire, asthis means an extensive subdivision of the eddy current paths andconsequently 'a considerable diminution of the losses.

The thickness of the iron wire used, and the number of the layers ofiron-Wire turns (provided a plurality of layersis needed), depend4entirely upon the frequency employed. In order to safeguard the surfacefrom oxidation, it is a recommendable plan to coat the surface withchromium, an amalgam, or some similar means. i

Instead of using a massive or solid conductor in the manner ashereinbefore described which is externally surrounded in the usualmanner by air orv another cooling medium, the said conductor could begiven the shape of a hollow body through the interior of which there ispassed a convenient cooling agent. The massive conductor could also bereplaced by this sort of arrangement,

.upon a massive or a cylindrical insulating body, there is first broughta layer or strat-l um of the current-conducting material to be used,whereupon the iron Wrapper, winding, ,or envelope is placed upon saidlayer.

Referring to the drawing, in Figs.` 1 and 2, a represents theconductorwhich may be copper, provided at its ends with eyes 1 and 2 forsecuring necessary connecting wires. A coating or covering b of magneticmate-l rial is shown upon the conductor a. This coating is quite thinand for purposes of illustration is one-tentli of one millimeter inthickness.

In Fig. 2 the conductor is bifilar, that is, it is bent backon itself tosave space. 'r

In Fig. 3, the conductor a is shown hollow, the hollow space beingdenoted by 10.

is practically limited by the amountof energy to be dissipated. Undercertain circumstances, it may be siiitable to wind the stretched wire insome constructionally appropriate form so that itoccupies less space.But in this regard, attention must be paid that by such wrapping orwinding-as is true of a simple coil--no increase in self-inductance willbe produced in the internal conductor. On the contrary, it is necessaryto always provide bifilar winding or wrapping. More suitable than thesimple stretched length or piece of conductor with lead-in at one endand lead-off at the opposite end is the bifilar arrangement. In otherwords, there should be at least onelto-andfro arrangement so that noloop field can be 'set up for the conductor.

As a stretched conductor in the foregoing sense, if the frequencies aresufficiently high, there can be used also an iron wire without specialwrapper, in view of the fact that the physical effect in such anarrangement is approximately the same asf before described for a currentconductor made of non-magnetic material. Y

Having described our invention, we are entitled to all modificationsthereof that fall fairly within the spirit and scope of the followingclaims:

. 1. A high frequency conductor comprising an inner nonmagneticconducting member, a thin magnetic layer surrounding said conductingmember and in direct contact therewith, said layer being designed toprovide maximum magnetic permeability irrespec tive of tensile strengthand means for neutralizing the'- leakage flux. which passes throughsaid, outer magnetic layer, said neutralizing means being provided inwinding said conductor bitilarl fashion.

2. A high frequency conductor comprising an inner nonmagnetic hollowcylindrical conducting member, a thm magnetic layer surrounding saidconducting member and in direct contact therewith, said layer beingadapted to provide maximum magnetic permeability irrespective of tensilestrength, in-

sulating material of fluid forni adapted to cool said Aconductorcontained within said hollow cylindrical conducting member, and meansfor neutralizing the leakage flux which passes through said outermagnetic layer, said neutralizing means being provided in winding saidconductor bitlar fashion.

3. A high frequency conductor compris- \ing, an inner nonmagnetic hollowcylindrical conducting member, a thin magnetic layer surrounding saidconductor and in direct 'contact therewith, said, layer being designedto providemaximum magnetic permeability irrespective of tensilestrength, and means for neutralizing the leakage flux which passesthroughl said outer layer, said neutralizing means being provided inwinding the conductor bifilar fashion.

MENDEL osNos. RICHARD y KUMMIGH.

